To determine the acute and memory B and T cell responses to oral cholera vaccine, studies will be conducted in adults (18-45 years) and children of different age groups (1 -5 years). For this part of the study, 25 adults, 25 toddlers (2-5 years old), and 25 under-two children will be vaccinated. For responses to Vivotif, we will only study adults (n=25) and toddlers (n-25).